Shares of Verizon rose 1.6 per cent to $48.75 in after-hours trading following the disclosure, in a US Securities and Exchange Commission filing, detailing Berkshire's US common stock investments as of March 31.

Shares of companies often rise after Berkshire reveals new stakes because some investors consider it a vote of confidence by Buffett and try to copy him.

Verizon "has shown that with several changes in leadership, the company performs and is a premium provider, if not the premium provider in the market," said analyst Roger Entner of Recon Analytics in Boston.

Buffett "likes people who can execute," Entner added.

Investor Daniel Loeb's Third Point LLC also opened a new stake in Verizon, buying 3.5 million shares.

Verizon declined to comment.

Berkshire's regulatory filing did not say whether the Verizon investment was made by Buffett himself, or by one or both of his portfolio managers, Todd Combs and Ted Weschler.

US regulators require large investors to disclose their stock holdings every quarter, and the disclosures can offer a window into their investment strategies.

Berkshire, a conglomerate with over 80 businesses ranging from ice cream to insurance, added to stakes in other companies, as well, including DaVita HealthCare Partners Inc and IBM Corp, among others.